1. Field of the Invention
This invention relates to shielded and wireless connectors for interconnecting individual electronic card assemblies. More particularly, this invention relates to card assemblies interconnections which allow signals of one assembly to be isolated from signals of other assemblies and any other signal going to or from that assembly.
2. Description of the Background Art
Surface mount and hybrid component technologies currently permit very high density individual electronic circuit board designs. Further, multilayer electronic circuit board technologies currently permit high frequency analog signals to be isolated from digital signals through the appropriate allocation of individual processing functions and/or electrical signals to individual layers of a multilayer board. Specifically, internal metallized layers within the circuit board are often used to isolate high frequency analog or digital signals of one layer from signals of another layer.
Unfortunately, the level of manufacturing technology presently available limits multilayer circuit board designs to approximately 10 to 12 layers. Thus, in many complex electronic systems, 10 to 12 layers are insufficient to allow high frequency analog and digital signals to be constrained to the layers of the multilayer circuit board. Several individual multilayer circuit boards must therefore be employed, in which high frequency analog signals are limited to some boards and digital signals limited to other boards. However, these individual circuit boards must then be interconnected to each other.
Typically, interconnection of individual circuit boards is accomplished using chassis-mounted circuit card connectors and cables (or wires). Alternatively, circuit card connectors may be mounted onto a printed circuit mother board allowing printed circuit daughter boards to be plugged into the connectors. As determined by the printed circuit on the mother board, each daughter board may be interconnected to adjacent daughter boards or to distant daughter boards located several connectors away. In either arrangement, the long interconnections between individual circuit boards reduce system electrical performance by introducing timing and phase shift errors and by compromising the isolation of high frequency analog signals from digital signals.
U.S. Pat. Nos. 4,710,133 and 4,806,110 disclose related types of electrical mother and daughter board edge connectors designed to minimize interference between circuit board signals and extraneous signals. U.S. Pat. No. 5,007,843 discloses another type of edge connector which employs connector elements each composed of a strand of metal wire wadded together to form a "button" of wadded wire. U.S. Pat. No. 5,007,843 also discloses a circuit board cable harness which employs button connector elements. Finally, as shown in U.S. Pat. No. 4,992,053, improved interconnection of circuit boards has been proposed through the use of a plurality of button connector assemblies, each comprising a pair of button connector elements positioned on opposing ends of a metal slug, with the button connector elements and the slug being positioned within a hole in a block of insulative material and with the circuit boards being bolted about the insulative material
In addition to signal isolation concerns, systems incorporating interconnecting signal wires or mother and daughter board arrangements, such as those discussed above, are difficult to design for very high inertial applications. Specifically, the interconnecting wires and the mother and daughter boards flex under the high inertial forces developed during periods of high shock or acceleration and are therefore subject to failure. Furthermore, metal covers that are often employed to shield individual circuit boards, also flex under the same conditions and are therefore also subject to similar failures.
In view of the foregoing, there presently exists a need for a shielded and wireless interconnection of individual circuit boards. There also exists a need for such shielded and wireless interconnection of circuit boards that is capable of withstanding very high inertial environments.
Therefore, it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art connectors and provides an improvement which is a significant contribution to the advancement of the circuit board interconnection art.
Another object of this invention is to provide an interconnection apparatus for circuit boards employing embedded feed-through connector assemblies that are fully shielded by the metal carrier in which they are embedded
Another object of this invention is to provide an interconnection apparatus for circuit boards in which the impedance of the dielectric inserts of each aligned connector assemblies may be selected so as to achieve an optimal impedance for that serial interconnection, much in the same manner of selecting the optimal impedance of a transmission line.
Another object of this invention is to provide an interconnection apparatus for circuit boards having the ability to survive very high levels of shock and/or acceleration in excess of 1000 times the force of gravity without circuit board failure.
Another object of this invention is to provide an interconnection apparatus for circuit boards employing embedded feed-through connector assemblies that are designed so as to also survive very high levels of shock and/or acceleration without degrading their electrical contact with the metal pads of the respective circuit boards.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.